MINERAL  PRODUCTS.

39

In  Arkansas  flint  pebbles  have  been  noted  at  many  places  in
Greene,  Craighead,  Poinsett,  Cross,  and  St.  Francis  counties,  along
Crowleys  Bulge,  which  is  paralleled  by  the  St.  Louis,  Iron  Mountain
&  Southern  Kailway.  From  4  to  T  miles  west  of  Paragould,  in
Greene  County,  where  a  public  road  crosses  the  highest  part  of  the
ridge,  beds  of  gravel  not  exceeding  5  feet  in  thickness  occur,  usually
overlain  by  1  to  5  feet  of  loam.  The  gravels  consist  chiefly  of  gray,
brown,  and  pink  angular  or  fairly  well-rounded  pebbles  of  flint  and
chert,  the  largest  6  inches  in  length,  and  a  considerable  percentage  of
white,  partly  rounded  to  smoothly  rounded  pebbles  of  quartz,  the
largest  1  inch  in  length.  An  exposure  on  the  property  of  Mrs.
Mahala  Shelton,  6  miles  southwest  of  Jonesboro,  in  Craighead
County,  on  the  south  side  of  one  of  the  small  headwater  streams  of
L’Anguille  Biver,  shows  from  4  to  11  feet  of  gravel,  consisting
mainly  of  angular  to  party  water-worn  brown  chert  pebbles  and
cobbles,  reaching  a  maximum  dimension  of  1  foot.  Bed,  pink,  gray,
and  black  chert  pebbles  and  a  few  smoothly  rounded  pebbles  of  pink
and  white  quartz  were  also  observed.  Excavation  for  road  material
1  mile  east  of  Wynne,  in  Cross  County,  just  south  of  the  St.  Louis,
Iron  Mountain  &  Southern  Kailway,  showed  16  feet  of  gravel,  consisting ­
  chiefly  of  angular  to  fairly  well  rounded  pebbles  and  cobbles
of  brown  and  gray  flint  and  chert  as  much  as  6  inches  in  length,  with
some  well-rounded  quartz  pebbles,  lying  in  a  matrix  of  coarse  reddish ­
  sand.  This  material  is  covered  by  about  10  feet  of  loam.
In  northeastern  Mississippi  gravels  carrying  abundant  flint  pebbles ­
  have  been  noted  in  Tishomingo  County,  a  locality  about  2%  to
3  miles  east  of  Iuka  being  especially  mentioned.  Some  of  these  deposits ­
  are  50  to  T5  feet  thick  and  cover  large  areas.  The  flints  are
only  in  part  well  rounded  and  portions  of  the  deposit  are  iron
stained.  The  gravel  is  extensively  excavated  for  use  in  road  making.
In  Texas  light  opalescent  to  black  flint  pebbles  are  abundant  at
several  localities.  They  are  well  exposed  along  the  river  bluffs  near
Austin,  Travis  County,  where  they  have  weathered  out  of  the  limestone. ­
  They  also  occur  along  Nueces  Biver  near  Oakville,  in  Live
Oak  County,  and  over  large  areas  near  Tilden,  in  McMullen  County.
Only  here  and  there  are  these  flints  well  rounded,  and  many  of  them
are  coated  with  a  thin  film  of  iron  oxide.
For  certain  kinds  of  tube  mill  grinding—as,  for  example,  the
grinding  of  feldspar  or  of  crystalline  quartz  for  making  pottery—
pebbles  practically  free  from  any  iron-bearing  mineral  must  be
used,  for  even  small  specks  of  iron-bearing  minerals  produce  stains
in  pottery  on  firing.  For  other  purposes,  however,  as,  for  example,
the  grinding  of  gold  ores  preparatory  to  cyanidation,  the  same  freedom ­
  from  iron  is  not  necessary,  and  rounded  pebbles  of  various  kinds
of  hard  rocks  collected  from  benches,  stream  beds,  or  gravel  deposits